Home | Help | Feedback | Subscriptions | Archive | Search | Table of Contents

This Article Abstract Full Text (PDF, 1390K) PPT slides of all figures Alert me when this article is cited Citation Map Services Email this article Similar articles in this journal Similar articles in PubMed Alert me to new content in the JCB Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Patton, B. L. Articles by Sanes, J. R. Search for Related Content PubMed PubMed Citation Articles by Patton, B. L. Articles by Sanes, J. R. Social Bookmarking                            What's this?

© The Rockefeller University Press, 0021-9525/1997//1507 $5.00
The Journal of Cell Biology, Volume 139, Number 6, , 1997 1507-1521

Distribution and Function of Laminins in the Neuromuscular System of Developing, Adult, and Mutant Mice

Bruce L. Patton^*, Jeffrey H. Miner^*,, Arlene Y. Chiu, and Joshua R. Sanes^*

^* Department of Anatomy and Neurobiology, Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri 63110; and Division of Neuroscience, Beckman Research Institute of the City of Hope, Duarte, California 91010

Laminins, heterotrimers of , β, and chains, are prominent constituents of basal laminae (BLs) throughout the body. Previous studies have shown that laminins affect both myogenesis and synaptogenesis in skeletal muscle. Here we have studied the distribution of the 10 known laminin chains in muscle and peripheral nerve, and assayed the ability of several heterotrimers to affect the outgrowth of motor axons. We show that cultured muscle cells express four different chains (1, 2, 4, and 5), and that developing muscles incorporate all four into BLs. The portion of the muscle's BL that occupies the synaptic cleft contains at least three chains and two β chains, but each is regulated differently. Initially, the 2, 4, 5, and β1 chains are present both extrasynaptically and synaptically, whereas β2 is restricted to synaptic BL from its first appearance. As development proceeds, 2 remains broadly distributed, whereas 4 and 5 are lost from extrasynaptic BL and β1 from synaptic BL. In adults, 4 is restricted to primary synaptic clefts whereas 5 is present in both primary and secondary clefts. Thus, adult extrasynaptic BL is rich in laminin 2 (2β11), and synaptic BL contains laminins 4 (2β21), 9 (4β21), and 11 (5β21). Likewise, in cultured muscle cells, 2 and β1 are broadly distributed but 5 and β2 are concentrated at acetylcholine receptor–rich "hot spots," even in the absence of nerves. The endoneurial and perineurial BLs of peripheral nerve also contain distinct laminin chains: 2, β1, 1, and 4, 5, β2, 1, respectively. Mutation of the laminin 2 or β2 genes in mice not only leads to loss of the respective chains in both nerve and muscle, but also to coordinate loss and compensatory upregulation of other chains. Notably, loss of β2 from synaptic BL in β2^–/– "knockout" mice is accompanied by loss of 5, and decreased levels of 2 in dystrophic 2^dy/dy mice are accompanied by compensatory retention of 4. Finally, we show that motor axons respond in distinct ways to different laminin heterotrimers: they grow freely between laminin 1 (1β11) and laminin 2, fail to cross from laminin 4 to laminin 1, and stop upon contacting laminin 11. The ability of laminin 11 to serve as a stop signal for growing axons explains, in part, axonal behaviors observed at developing and regenerating synapses in vivo.

Abbreviations used in this paper: AChR, acetylcholine receptors; BL, basal lamina; E, embryonic day.

IN skeletal muscles, a continuous sheath of basal lamina (BL)¹ surrounds each muscle fiber and passes through the synaptic cleft at the neuromuscular junction. Thus, most of the BL separates the muscle fiber membrane from interstitial connective tissue, whereas a small fraction (0.1%) separates the muscle from the nerve. These extrasynaptic and synaptic portions of the BL play several important roles in the development and function of the muscle and the neuromuscular junction, respectively. Components of extrasynaptic BL regulate myogenesis in embryos, contribute to tensile strength in adults, and serve as a scaffold to orient regenerating myotubes after muscle damage. Components of synaptic BL organize differentiation of the pre- and postsynaptic membranes in embryos, inactivate neurotransmitter in adults, and guide reinnervation after nerve damage (for reviews see Sanes, 1994, 1995).

Key molecules in these processes are the laminins, glycoproteins that are major components of BLs in all tissues. Laminin was initially isolated from tumor-derived matrix as a trimer of 1, β1, and 1 chains (formerly A, B1, and B2; Chung et al., 1979; Timpl et al., 1979; Burgeson et al., 1994). A homologue of the 1 chain, originally called merosin and now renamed 2, was subsequently isolated from muscle and shown to be a major component of extrasynaptic BL (Lievo and Engvall, 1988; Ehrig et al., 1990). Similarly, β2 (originally s-laminin) was identified as a component of synaptic BL (Chiu and Sanes, 1984; Hunter et al., 1989a). Laminins containing the 2 chain are adhesive for myoblasts (Schuler and Sorokin, 1995), and recombinant laminin β2 fragments regulate outgrowth of motor axons (Hunter et al., 1989b; Porter et al., 1995). Thus, based on their distribution in vivo and their effects in vitro, the 2 and β2 chains were hypothesized to be involved in myogenesis and synaptogenesis, respectively. Recent genetic analyses in mice have provided strong support for these hypotheses: targeted mutation of the laminin β2 gene leads to aberrant structural and functional maturation of neuromuscular junctions (Noakes et al., 1995a), and a naturally occurring hypomorphic allele of laminin 2 (2^dy/dy) gives rise to severe muscular dystrophy (Sunada et al., 1994; Xu et al., 1994b). Some cases of human familial muscular dystrophy have also been shown to result from mutation of the laminin 2 gene (Hayashi et al., 1993; Helbling-Leclerc et al., 1995; Sunada et al., 1995; Nissinen et al., 1996).

Despite the strong evidence that laminins are crucial for neuromuscular development, it has been difficult to elucidate their precise roles for several reasons. First, additional laminin chains and a total of 11 β heterotrimers (laminins 1–11; Table I) have now been identified in vertebrates. The distribution of the new chains in muscle has not yet been reported, so the identity of the laminin trimers in synaptic and extrasynaptic BL remains unclear. Second, mutation of a single laminin or collagen IV chain gene leads to coordinate loss of some chains and compensatory retention of others in kidney BLs (Kashtan and Kim, 1992; Gubler et al., 1995; Noakes et al., 1995b; Cosgrove et al., 1996; Miner and Sanes, 1996). Similar interactions might occur in muscle, complicating analyses of the 2^dy/dy and laminin β2^–/– phenotypes. Third, laminins 2 and β2 are present in the BLs of peripheral nerve as well as muscle (Sanes et al., 1990), so mutant phenotypes might reflect both neurogenic and myogenic defects. Finally, functional studies of laminin β2 have been limited to recombinant fragments (Hunter et al., 1989b; Porter and Sanes, 1995; Porter et al., 1995) and a single heterotrimeric form (laminin 4; Brandenberger et al., 1996). It may be inappropriate to extrapolate from the activities of these preparations to those of synaptic laminins.

	Materials and Methods

Top Abstract Materials and Methods Results Discussion References

 
Animals
Mice deficient in laminin β2 and littermate controls were generated and genotyped as described by Noakes et al. (1995a). When maintained on high-fat rodent chow after weaning, the β2^–/– mutants do not gain weight but do live until P28–P35. Mice homozygous for a mutation in the laminin 2 gene (Lama2^dy/dy) and littermate controls were purchased from Jackson Laboratories (C57BL/6J-Lama2dy/dy; Bar Harbor, ME). Embryos were taken from timed pregnant ICR or C57BL6 mice, bred in our colony.

Antibodies
Monoclonal antibodies to rat laminin β1 (C21 and C22), β2 (D5, D7, D19, and D27), and 1 (D18) chains, rabbit antisera to recombinant laminin 4 and 5 chains, and a guinea pig antiserum to laminin β2 were produced in this laboratory and have been described previously (Sanes and Chiu, 1983; Hunter et al., 1989a; Sanes et al., 1990; Green et al., 1992; Miner et al., 1997). Rat monoclonal antibodies to mouse laminin 1 (clones 198 and 200; Sorokin et al., 1992) were gifts from L. Sorokin (Institute for Experimental Medicine, Erlangen, Germany). Rabbit antiserum to human laminin 2, which cross-reacted with the mouse protein, was provided by P. Yurchenco (Robert Wood Johnson Medical School, Piscataway, NJ; see Miner et al., 1997). Rabbit antiserum to mouse laminin 3 (Aberdam et al., 1994) was a gift from D. Aberdam (Institut National de la Sante et de la Recherche Medicale [INSERM] U385, Nice, France). Rabbit antiserum to laminin-5 (3β32) was a gift of R. Burgeson (Massachusetts General Hospital, Charlestown, MA). A rat monoclonal antibody to laminin β1 (5A2; Abrahamson et al., 1989; Martin et al., 1995) was a gift from D. Abrahamson (University of Alabama, Birmingham, AL). Rat anti–mouse laminin 1 was purchased from Chemicon International, Inc. (Temecula, CA). FITC- and HRP-conjugated, goat anti–rabbit antibodies were from Boehringer Mannheim Corp. (Indianapolis, IN); FITC-conjugated, goat anti–rat antibodies were from Cappel/Organon Teknika (Durham, NC); Cy3-goat anti–rabbit antibodies were from Jackson Immunoresearch Laboratories (West Grove, PA); biotinylated, goat anti–guinea pig antibodies were from Sigma Chemical Co. (St. Louis, MO); and HRP-avidin was from Zymed Labs Inc. (South San Francisco, CA).

All results on laminin 1 were confirmed with two monoclonal antibodies, 198 and 200, which react with distinct epitopes (Sorokin et al., 1992). All results on laminin 5 (3β32) were obtained using an antibody that recognizes all three chains (Marinkovich et al., 1992), and were confirmed using an antibody specific for the 3 chain, which binds an epitope present in both 3A and 3B isoforms (Aberdam et al., 1994; Miner et al., 1997). To date, β3 and 2 have been found only in association with 3 (Table I), so absence of 3 provides indirect support for absence of β3 and 2. These antibodies stained a subset of lung BLs intensely in our hands (data not shown). All results on laminins 4 and 5 were confirmed with two separately generated rabbit antisera to each chain; the specificity of these sera has been documented previously (Miner et al., 1997).

Laminin Heterotrimers
Laminin 1 (1β11) from the mouse EHS tumor matrix, and laminin 2 (2β11) from human placenta, were purchased from GIBCO BRL/Life Technologies (Gaithersburg, MD). Purified laminin 4 (2β21) and a second sample of laminin 2, both purified from human placenta, were generous gifts of Y.-S. Cheng and P. Yurchenco (Robert Wood Johnson Medical School; Cheng et al., 1997). Laminin 11 (5β21) was purified from the conditioned medium of rat Schwannoma D6P2T cells by a modification of the method described by Chiu et al. (1992). By immunoblotting using antibodies described above, the "laminin 11" fraction was found to be rich in 5, β2, and 1, but to contain little or no 1, 2, 3, 4, or β1.

Neuronal Cultures
To generate patterned substrates, plastic culture dishes were first coated with a thin layer of nitrocellulose (type BA85; Schleicher and Schuell, Keene, NH) (Lagenaur and Lemmon, 1987). A pattern was then formed by applying 1-µl drops of test proteins in PBS supplemented with 2 mM EDTA and 1 mg/ml sulforhodamine-101 (Sigma Chemical Co., St. Louis, MO). After incubation in a humidified chamber for 1–5 h at room temperature, dishes were flushed repeatedly to remove unbound material, and then coated for 2 h at room temperature with laminin 1 (20 µg/ml in PBS; GIBCO BRL) to support cell attachment and initiate neurite outgrowth. Dishes were rinsed with PBS or PBS/BSA and used immediately for neurite outgrowth assays.

Chick ciliary ganglia were dissected from E8-9 embryos, digested in 0.05% trypsin in Ca²⁺/Mg²⁺-free HBSS for 15 min at 37°C, and dissociated by trituration. Cells were washed in MEM (No. 11095; GIBCO BRL) containing 10% FCS (Hyclone, Logan, UT), and resuspended in MEM supplemented with 25 mM Hepes, 7% heat inactivated horse serum (Hyclone), 3% FCS, 1 mM glutamine, 1 mM glucose, penicillin, and streptomycin. Aliquots of 30 µl containing 0.2 ganglion equivalent (800 neurons) were suspended from culture dish lids in a 37°C, 7% CO₂ incubator. Cell clusters formed in 3–6 h within the hanging drops. The clusters were then transferred to culture dishes and positioned near patches of test substrates. Neurons were grown for 30–36 h in culture medium containing 1% chick eye extract (Nishi and Berg, 1981), and then fixed with formaldehyde.

For analysis, cultures were viewed with phase optics to visualize neurites and rhodamine optics to visualize the substrate border. Two categories of neurites were counted. Group A were those that extended on laminin 1 and terminated on or near the substrate border, in a swath extending from 50 µm onto the laminin 1 to 10 µm over onto the test substrate. Group B were neurites that began on laminin 1 and extended greater than 10 µm beyond the border. Neurites initiated on the test substrate, and neurites that did not approach a border were not scored. Inhibition of crossing was calculated as (A ÷ [A + B]).

Because this assay was designed to test the behavior of neurites in response to various laminins, it was crucial to rule out the possibility that test substrates were acting indirectly by reducing the concentration of laminin 1 available to the neurons. To this end, we stained patterned substrates with antisera specific for laminin 1, and found that laminin 1 immunoreactivity was not detectably decreased in regions that had previously been spotted with BSA solutions of 1 mg/ml or laminins 2, 4, or 11 at 40 µg/ml. Biological effects reported below for laminins 4 and 11 were observed at <40 µg/ml.

Muscle Cell Culture
The RMo rat muscle cell line (Merrill, 1989) was cultured in F10 medium containing 15% FCS and 3% chick embryo extract. Nearly confluent cultures were induced to differentiate and form myotubes by medium replacement with DME containing 4% horse serum. After 6 d a soluble 95-kD fragment of rat agrin (Ferns et al., 1993) was added to cultures for 24 h to promote clustering of acetylcholine receptors (AChRs) and associated proteins. C2 mouse muscle cells were cultured as described in Martin et al. (1995).

Immunohistochemistry
Freshly frozen tissues were sectioned in a cryostat at 4–8 µm and fixed with 2% paraformaldehyde in PBS for 10 min. Fixed sections were blocked with 0.1 M glycine in PBS (10 min), and incubated overnight at 4°C with antibodies diluted in a solution of 2% BSA and 0.1% (wt/vol) saponin (Sigma Chemical Co.) in PBS. After washing, bound antibodies were detected with species-specific, fluorochrome-conjugated secondary antibodies, and then washed, mounted in glycerol containing p-phenylenediamine, and observed with epifluorescent illumination. Where appropriate, rhodamine--bungarotoxin (50 nM; Molecular Probes, Eugene, OR) was included with the second antibodies, to label AChRs. Rabbit antilaminin 4 and guinea pig anti-β2 recognized only denatured antigen (Miner et al., 1997), so sections to be labeled with these antibodies were pretreated with 0.05% SDS in PBS at 50°C for 20 min. AChR were labeled in denatured sections by incubating sections in rhodamine--bungarotoxin both before fixation and after denaturation.

Immunoblotting and Immunoprecipitation
Samples were heated to 95°C for 5 min in SDS-PAGE sample buffer, with or without the reducing agent DTT, then subjected to SDS-PAGE on 7% (reduced) or 3.5% (nonreduced) gels. Proteins were transferred to nitrocellulose membranes (Schleicher and Schuell) in 25 mM Tris, pH 9.5, 130 mM glycine, 0.1% SDS, and 10% (vol/vol) methanol at 320 mA for 24 h at 4°C. Positions of major bands were visualized with Ponceau S and marked. After blocking with a solution of 5% nonfat dry milk (Schnucks, St. Louis, MO) and 0.3% Tween-20 in PBS, filters were cut into strips and incubated with antibodies overnight. Bound mouse and rabbit antibodies were detected with HRP second antibodies and chemiluminescent substrates (Renaissance; DuPont-NEN, Boston, MA). Guinea pig antibodies were detected with biotinylated second antibody and HRP-avidin.

For immunodepletion, aliquots of a protein A–Sepharose CL-4B conjugate (Pharmacia Biotechnology Inc., Piscataway, NJ) were loaded with either antilaminin 5 or preimmune serum (1.5 µl/µl resin), blocked with 2 mg/ml BSA (immunoglobulin-free; Sigma Chemical Co.), and then washed extensively with PBS plus 2 mM EDTA. Samples of laminin 11 were then added (0.25 µg/µl resin) and incubated 6 h or overnight at room temperature. The supernatant was withdrawn and tested for effects on neurite outgrowth as described above.

	Results

Top Abstract Materials and Methods Results Discussion References

 
Diversity of Laminin Chains in Adult Muscle and Nerve
We first asked which of the 10 known laminin chains (1–5, β1–3, 1, and 2) were present in the BL that ensheathed adult mouse muscle fibers. Antibodies to the 2, β1, and 1 chains intensely stained this BL (Fig. 1, a, b, and e). In contrast, 1, 3, β3, and 2 were undetectable in muscle (Fig. 1, d and f). The 4, 5, and β2 chains were also undetectable in extrasynaptic BL (Fig. 1, c, g, and h), although they were present at synaptic sites, as detailed below. Thus, consistent with previous reports (Engvall et al., 1990; Sanes et al., 1990; Vachon et al., 1996) and subject to caveats discussed below (see Discussion), the predominant laminin in adult muscle fiber BL appears to be the 2β11 heterotrimer, laminin 2 (Table I).

View larger version (71K): [in this window] [in a new window] [Download PPT slide]   Figure 1 Laminins of adult muscle fiber BL. Sections of adult mouse intercostal muscle were stained with antibodies specific for the indicated laminin chains. Muscle fiber BL was rich in the 2, β1, and 1 chains, but contained little or no 1, 3–5, β2, β3, or 2. Capillary BL (examples shown by arrows) was 4-, 5-, β1-, and 1-positive, and arteriolar BL contained β2 (A in c), 5, and 1 (not shown). Bar, 25 µm.

View larger version (67K): [in this window] [in a new window] [Download PPT slide]   Figure 2 Laminins of adult peripheral nerve. Sections of adult mouse intercostal muscles were stained with antibodies specific for the indicated laminin chains, and the internal intercostal nerves examined. Endoneurial BL (surrounding individual axon– Schwann cell units) was rich in the 2, β1, and 1 chains. Perineurial BL, surrounding fascicles of nerve fibers, was rich in 4, 5, β2, and 1. Neither contained detectable 1, 3, β2, or 2. Bar, 50 µm.

Differential Distribution of Laminin Chains in Synaptic BL
Three BLs with distinct cellular origins are joined at the edge of the neuromuscular junction (Fig. 3 a): extrasynaptic BL (produced by muscle cells and fibroblasts), Schwann cell BL (produced by Schwann cells and fibroblasts), and the BL of the synaptic cleft (produced by nerve and muscle) (Sanes, 1994, 1995). Moreover, ultrastructural studies of membrane and cytoskeletal proteins have defined two distinct domains within the synaptic cleft; AChRs, rapsyn, and utrophin are concentrated in what are called primary clefts, at the crests of junctional folds, whereas neural cell adhesion molecule (N-CAM), sodium channels, and ankyrin are concentrated along the sides of the folds in secondary clefts (Fertuck and Salpeter, 1976; Covault and Sanes, 1986; Flucher and Daniels, 1989; Bewick et al., 1992). It therefore seemed possible, but had not been shown, that BLs of the primary and secondary clefts were molecularly distinct as well.

View larger version (49K): [in this window] [in a new window] [Download PPT slide]   Figure 3 Laminins of adult synaptic BL. (a) Sketch of the neuromuscular junction, showing extrasynaptic, synaptic cleft, and Schwann cell BLs, and the distinct locations of BLs in primary and secondary clefts. (b) Summary of results obtained by confocal microscopy. Constituent heterotrimers deduced from the chain composition are also shown. (c–l) Sections of adult muscle, double labeled with contrasting fluorophores and photographed separately as indicated. The resulting images were combined using Photoshop (Adobe Systems, Mountain View, CA) (c''– l'') with the view in c–l shown in green and the view in c'–l' shown in red. -Bungarotoxin, which stains AChRs, marks the crests of junctional folds. By reference to this AChR-rich region, the BLs of extrasynaptic regions, Schwann cells, and the troughs of junctional folds (i.e., arrows in j') can be distinguished. Bar in l is 8 µm for c–h and 5 µm for i–l.

Three laminin chains (2, 4, and 5) were present at synaptic sites, but each had a distinct distribution. The 2 chain was codistributed with 1, being present in the extrasynaptic, primary cleft, junctional fold, and Schwann cell BLs (Fig. 3, c and g). The 4 chain was present in Schwann cell and primary cleft BLs, but was absent from extrasynaptic BL and from the BL of junctional folds (Fig. 3 i). In contrast, 5 was present in both primary cleft and junctional fold BLs, but was absent from extrasynaptic and Schwann cell BLs (Fig. 3 k). β1 was present in extrasynaptic and Schwann cell but not synaptic BLs (Fig. 3 d; see Sanes et al., 1990), whereas β2, like 5, was present in crest and fold BLs (Fig. 3 e). Laminins 1, 3, β3, and 2 were undetectable (Fig. 3, f and h; and data not shown).

To confirm these localizations, we used species-specific second antibodies to compare the distributions of pairs of laminin chains. For example, Fig. 3 j shows a section double labeled with antibodies to 4 and 1. Codistribution of the two chains in primary cleft and Schwann cell BLs is evident, as is the extension of 1 into the 4-free junctional folds. Double labeling for β2 and 5 confirmed that these two chains are codistributed throughout synaptic BL (Fig. 3 l).

Together, these observations reveal that each of the four BLs that abut synaptic sites bears a distinct complement of laminin chains: 2, β1, and 1 extrasynaptically (laminin 2); 2, 4, 5, β2, and 1 in the primary cleft (laminins 4, 9, and 11); 2, 5, β2, and 1 in the BL of junctional folds (laminins 4 and 11); and 2, 4, β1, and 1 in the BL that covers Schwann cells (laminins 2 and 8; Fig. 3 b).

Laminin Isoform Transitions in Developing Muscle
In some tissues, it has been shown that the complement of laminin chains in individual BLs changes during development (Jaakkola et al., 1993; Miner and Sanes, 1994; Virtanen et al., 1995, 1996; Miner et al., 1997). We therefore asked whether the laminin chains present when muscles and neuromuscular junctions are forming differed from those present in adult synaptic and extrasynaptic BL. We used intercostal muscles for this study because myogenesis, synaptogenesis, and BL formation have all been intensively studied in these muscles (see Kelly and Zacks, 1969a, b; Chiu and Sanes, 1984; Rosen et al., 1992).

Intercostal myoblasts begin fusing to form an initial cohort of myotubes, called primary myotubes, on embryonic days (E) 10 and 11, and the myotubes soon begin to assemble a BL. By E 11.5, numerous patches of BL are present on myotube surfaces, but a continuous lamina is not yet present (see Rosen et al., 1992 for references). These patches of BL contained 2, 5, β1, and 1 chains (Fig. 4, a, c, and f; and data not shown). The 3, 4, β2, β3, and 2 chains were undetectable (Fig. 4, d and e; and data not shown). Thus, the BL of newly formed myotubes contains laminin 10, as well as the adult trimer, laminin 2.

View larger version (94K): [in this window] [in a new window] [Download PPT slide]   Figure 4 Laminins of embryonic muscle. Sections of intercostal muscle from E 11.5 (a–f) or E 15 (g–r) embryos were stained with antibodies specific for the indicated laminin chains. Some sections were also double labeled with rhodamine--bungarotoxin (m'–r'). The patchy BL that partially coats myotubes at E 11.5 contains 2, 5, and 1 chains and, in areas abutting ribs (arrowheads), 1. Note that the section shown in b and c was double labeled with anti-1 and anti-2, showing that 1 is present in a subset of 2-containing BLs. At E11, 4 is detectable only in blood vessels (e, arrows). By E 15, the BL is continuous, and contains 4 in addition to 2, 5, and 1. The and chain complement of synaptic and extrasynaptic BL is qualitatively similar at this age (m– r), although β2 is already selectively localized to synaptic sites (data not shown). Bar in r represents 20 µm for a–f, 40 µm for g–l, and 16 µm for m–r.

BL deposition around primary myotubes continues between E 11 and 13. In addition, a second cohort of myotubes, called secondary myotubes, begins to form on E 14. By E 15, most myotubes bear a continuous BL sheath. As on E 11.5, this BL was rich in laminins 2, 5, β1, and 1, and 1 remained confined to the ends of myotubes (Fig. 4, g–i, and l; and data not shown). In contrast, levels of 4 increased dramatically after E 11.5, and this chain was present throughout all myotube BLs by E 15 (Fig. 4 k). Thus, laminin 8 appears to join laminins 2 and 10 as primary myotubes mature and secondary myotubes form.

Synaptogenesis begins in intercostal areas at E 13, and rudimentary neuromuscular junctions are readily detectable by E 14 (Kelly and Zacks, 1969b; Noakes et al., 1993). To assess early stages in the formation of synaptic BL, we double-labeled sections of E 15 intercostal with antilaminins plus rhodamine--bungarotoxin. The 2, 4, 5 and 1 subunits were all present in synaptic as well as extrasynaptic areas. Interestingly, 2, 4, and 1 appeared to be enriched in synaptic BL, but 5 did not (Fig. 4, m–r). As reported previously for rat intercostals (Chiu and Sanes, 1984), the β2 chain appeared soon after AChR clusters formed, and was restricted to synaptic sites at all stages, whereas β1 was present both synaptically and extrasynaptically at early stages of synaptogenesis (data not shown; note that the C1/C4 and C21/C22 antigens studied by Chiu and Sanes, are now known to be laminins β2 and β1, respectively [Sanes et al., 1990]).

Further changes in the composition of muscle BL occurred perinatally as myotubes matured into myofibers. Extrasynaptic levels of 4 and 5 were markedly lower at birth than at E 15, and neither subunit was detectable by the end of the first postnatal week. At the synapse, the intensity of 5 staining rose postnatally, while levels of 4 remained modest, and the β1 subunit was gradually lost from these regions. The β2 subunit remained confined to synaptic sites, and levels of 2 and 1 remained high both synaptically and extrasynaptically throughout development (data not shown). We also noted one developmental change in the BL of intramuscular nerves during this period: in embryos and during the first 2 postnatal wk, endoneurial BL contained 4 as well as 2, whereas adult endoneurium contained only 2 (data not shown; compare Figs. 2 g and 8 k).

In summary, the laminin chain composition of both extrasynaptic and synaptic BL changes during development, but in different ways. The 2 and 1 chains are present in both domains at all stages of development; 4 and 5 are initially present throughout the BL, and then lost from extrasynaptic BL; the β1 chain is initially ubiquitous, and then lost from synaptic BL; and β2 is confined to synaptic sites from its first appearance. From the perspective of deduced trimeric structure, laminin 2 predominates extrasynaptically at all stages, but is joined transiently by laminin 1 near the ends of fibers and by laminins 8 and 10 throughout the fiber length. Synaptically, the embryonic presence of β1 suggests that the β1-containing trimers (laminins 2, 8, and 10) are present initially but then lost, whereas the β2-containing trimers (laminins 4, 9, and 11) appear slightly later and are retained.

Production of Laminins 4 and 5 by Muscle Cells
To understand how laminins act, it is important to know which cells make them. This issue is of particular importance for synaptic BL, which is known to contain contributions from both muscle and nerve (Sanes, 1995), and might also contain products of Schwann cells. Myogenic cells are known to synthesize the laminin 1, 2, β1, β2, and 1 chains (Green et al., 1992; Kroll et al., 1994; Schuler and Sorokin, 1995; Vachon et al., 1996), but synthesis of 4 or 5 by muscle has not yet been reported. To address this issue, we used the rat muscle cell line, RMo (Merrill, 1989). We have previously shown that RMo cells express β1, β2, and 1 chains, and hitherto unidentified -like chains (Green et al., 1992). Here, we asked whether the -like chains corresponded to 4 or 5.

Proteins of RMo myotubes were separated by SDS-PAGE, and then immunoblotted. Antisera to laminin 4 recognized a protein of 200 kD, and antisera to 5 recognized a protein of 400 kD (Fig. 5 a, lanes 3 and 4). These apparent molecular weights were similar to those obtained previously from rat lung and kidney tissue extracts immunoblotted with these same antisera (Miner et al., 1997). Antiserum to laminin 1 recognized bands of 400, 220, and 200 kD (Fig. 5 a, lane 2), presumably representing the 1, β1, and 1 chains, respectively. As expected, anti-β2 bound to a protein of 190 kD (Fig. 5 a, lane 5). Non-immune serum showed no reaction with any of the laminin chains (Fig. 5 a, lane 1). Thus, muscle cells synthesize not only the laminin 1, 2 (see below), β1, β2, and 1 chains, but also 4 and 5.

View larger version (163K): [in this window] [in a new window] [Download PPT slide]   Figure 5 Synthesis and distribution of laminin chains in RMo myotubes. (a) Immunoblot of cell lysate with nonimmune serum (lane 1), antilaminin 1 (lane 2), antilaminin 4 (lane 3), antilaminin 5 (lane 4), or antilaminin β2 (lane 5). (b–d) Micrographs of cultures labeled with antibodies specific for the indicated laminin chains. The cultures shown in b and c were counterstained with rhodamine--bungarotoxin (b', c'), and the culture shown in d was counterstained with antilaminin β2 (d'). The 2 (e), β1 (not shown), and 1 (f) chains are broadly distributed on the myotube surface, whereas 5 and β2 are colocalized in small patches that abut AChR-rich domains on the myotube membrane. Bar in f is 20 µm for b, c, e, and f, and 30 µm for d.

We also immunostained C2 and primary mouse myotubes with antibodies to laminin 5. In contrast to results obtained with RMo cells, 5 was associated with both AChR-rich and AChR-poor regions of myotubes in these preparations (data not shown). Since 5 becomes restricted to synaptic sites in vivo as development proceeds, it may be that postsynaptic differentiation progresses to a later stage in RMo than in C2 or primary myotubes.

Compensation and Coregulation in Laminin 2 and β2 Mutants
Mice with mutations in two laminin chain genes are available: naturally occurring 2^dy/dy mice, in which levels of 2 are markedly reduced (Arahata et al., 1993; Sunada et al., 1994, 1995; Xu et al., 1994a,b), and β2^–/– mice, in which a null mutation was introduced by homologous recombination (Noakes et al., 1995a). The 2^dy/dy mice exhibit severe muscular dystrophy with only minor perturbation of neuromuscular junctions (Carbonetto, 1977; Banker et al., 1979; Law et al., 1983; Desaki et al., 1995) whereas synaptic maturation is markedly aberrant but muscles are nearly normal in β2^–/– mice (Noakes et al., 1995a). These results implicate the laminin 2 and β2 chains in myogenesis and synaptogenesis, respectively. However, interpretation of the mutant phenotypes requires understanding which laminin trimers are present in the BLs of mutant muscle and peripheral nerve. We therefore assessed the distribution of other laminin chains in 2^dy/dy and β2^–/– muscle.

In extrasynaptic BL of 2^dy/dy muscles, laminin 2 immunoreactivity was markedly reduced in intensity and was patchy rather than continuous in distribution (Fig. 6 j). This incomplete loss has been noted previously, and is consistent with dy/dy being an allele that decreases 2 levels but does not affect the size of the 2 polypeptide (Sunada et al., 1994; Xu et al., 1994a). In contrast, levels of β1 and 1 immunoreactivity were only slightly lower in 2^dy/dy muscles than littermate control muscles (Fig. 6, a, b, g, and h), consistent with previous reports in 2^dy/dy mice (Sunada et al., 1994; Xu, et al., 1994a) and in human merosin-deficient dystrophy (Hayashi et al., 1993; Sewry et al., 1995). Assuming that native laminins are all heterotrimers (Burgeson et al., 1994), this pattern implies a compensatory increase in the level of another chain. Indeed, immunoreactivity for laminin 4 was undetectable in controls but intense in 2^dy/dy extrasynaptic BL (Fig. 6, e and k). This compensation was specific, in that the laminin 1, 3, 5, and β2 chains remained undetectable extrasynaptically (Fig. 6, c, f, i, and l; and data not shown). Thus, laminin 8 may compensate for the loss of laminin 2 in 2^dy/dy muscle.

View larger version (92K): [in this window] [in a new window] [Download PPT slide]   Figure 6 Laminins of 2dy/dy and β2–/– muscle. Sections of intercostal muscle from 2dy/dy (g–l) or β2–/– mutants (m–r) or from controls (a–f) were stained with antibodies specific for the indicated laminin chains. In 2dy/dy muscle, partial loss of 2 leads to appearance or retention of 4 but not 5. Extrasynaptic BL of β2–/– mutants does not differ from that of controls. Arrows mark synaptic sites (localized with rhodamine- -bungarotoxin; not shown) in c, h, i, l, and r. Bar in r is 40 µm for a–l and 20 µm for m–r.

View larger version (56K): [in this window] [in a new window] [Download PPT slide]   Figure 7 Laminins of synaptic BL in 2dy/dy and β2–/– mutants. Sections of intercostal muscle from adult 2dy/dy (a–d) or β2–/– mutants aged 14 d (e–h) were double stained with antibodies specific for the indicated laminin chains (a–h) plus rhodamine--bungarotoxin (a'–h'). Specific loss of 2 from synaptic sites in 2dy/dy leads to increased levels of 4, but no detectable changes in the distribution of 5 or β1. Loss of β2 from synaptic sites in β2–/– leads to coordinate loss of 5 and increased levels of β1 but not marked changes in the distribution of 2 or 4. Bar, 15 µm.

To extend our analysis of compensation and coregulation, we assessed the distribution of laminin chains in 2^dy/dy and β2^–/– intramuscular nerves. As detailed above, 2 is normally found in endoneurial BL and β2 in perineurial BL. In endoneurial BL of the 2^dy/dy mutant, levels of 2 were markedly reduced and levels of 4 were increased (Fig. 8, d and e). Thus, 4 appears to compensate for 2 in nerve as it does in muscle. In perineurial BL of the β2^–/– mutant, β2 and 5 were both absent and 4 was considerably reduced (Fig. 8, i–l). Thus, 5 and β2 appear to be coregulated in nerve as in muscle. The laminin compositions of perineurial BL in the 2^dy/dy mutant and of endoneurial BL in the β2^–/– mutant were qualitatively normal (compare Figs. 2 and 8).

View larger version (67K): [in this window] [in a new window] [Download PPT slide]   Figure 8 Laminins of peripheral nerve in 2dy/dy and β2–/– mutants. Intramuscular nerves from intercostal muscles were stained with antibodies specific for the indicated laminin chains. Wild-type nerves are shown in Fig. 2. Loss of 2 in 2dy/dy leads to a compensatory increase in 4 immunoreactivity in the endoneurium. Loss of β2 in β2–/– leads to a coordinate loss of 5, and reduction in 4 from the perineurium. Bar, 50 µm.

Initially, we plated dissociated ciliary neurons on substrates coated with purified laminin 1, 2, 4, or 11, and then fixed and viewed them 30 h later. Most neurons extended neurites on laminins 1, 2, or 4, as reported previously (Weaver et al., 1995; Brandenberger et al., 1996) (Fig. 9, a and b). In contrast, neurons adhered to but did not extend neurites on laminin 11 (Fig. 9 c). Likewise, little outgrowth was observed when neurons were plated on mixtures of laminins 1 and 11, indicating that laminin 11 inhibited neurite outgrowth and did not merely lack outgrowth-promoting activity (data not shown). In this respect, laminin 11 behaved like recombinant β2 fragments, which we have previously shown to support adhesion of, but inhibit outgrowth from ciliary motoneurons (Porter et al., 1995).

View larger version (159K): [in this window] [in a new window] [Download PPT slide]   Figure 9 Growth of ciliary neurites on laminins (a–c). Neurons from embryonic chick ciliary ganglia were plated on substrates coated with laminin 1 (20 µg/ml; a), laminin 4 (20 µg/ml; b) or laminin 11 (30 µg/ml; c). Neurites extend on laminins 1 and 4 but only seldom on laminin 11. (d–l) Clusters of ciliary neurons were plated on patterned substrates, consisting of fields of laminin 1 and spots in which the laminin was coated atop test substrates: laminin 1 (100 µg/ml; d), laminin 2 (50 µg/ml; e), laminin 4 (50 µg/ml; f and g), laminin 11 (50 µg/ml; h, j and k), or BSA (100 µg/ml; i). In j and k, the laminin 11 was denatured by UV irradiation (j), or heating (k) before laminin 1 was applied. To mark borders, the test substances were mixed with the fluorescent dye sulforhodamine. Fields were photographed with a combination of phase and rhodamine optics, so that areas bearing test substrate appear bright. Neurons were plated on laminin 1 in d–f and h–k, and on the test substrate in g. Neurites cross freely over borders of additional laminin 1, laminin 2, BSA, or denatured laminin 11. Neurites growing on laminin 1 also cross freely onto a laminins 1 and 4 mixture, but neurites growing on the mixture seldom cross onto laminin 1. Neurites growing on laminin 1 seldom cross onto the laminins 1 and 11. Bar, 150 µm.

View larger version (16K): [in this window] [in a new window] [Download PPT slide]   Figure 10 Ciliary neurites distinguish laminin 11 from laminins 1, 2, and 4. (a) The frequency with which neurites growing on laminin 1 crossed onto a mixture of the indicated composition was determined as illustrated in Fig. 9 and detailed in Materials and Methods. Concentrations of proteins were as given in Fig. 9 legend. (b) Absorption with anti-5 coupled to protein A–agarose depleted the inhibitory activity in laminin 11. Treatment of the laminin 11 with preimmune serum (from the same rabbits) plus protein A–agarose had little or no effect. Bars show values from 21 to 80 neurites (mean = 53) in A, and 67–80 neurites (mean = 75) in B.

	Discussion

Top Abstract Materials and Methods Results Discussion References

 
In previous studies, we have analyzed the distribution, regulation, and function of the laminin β chains in muscle (Chiu and Sanes, 1984; Hunter et al., 1989a,b; Sanes et al., 1990; Noakes et al., 1995a; Porter et al., 1995). Here, we have extended these analyses to the chains, with special emphasis on the newly discovered 4 and 5. Our main results are as follows. (a) Cultured muscle cells express four different chains (1, 2, 4, and 5), and developing muscles incorporate all four into BLs, each in a distinct pattern. (b) Synaptic and extrasynaptic BL acquire distinct complements of laminin chains as development proceeds: 2, 4, 5, and β1 are initially present both synaptically and extrasynaptically, whereas β2 is restricted to synaptic BL from its first appearance; 2 remains broadly distributed; 4 and 5 become restricted to synaptic BL; and β1 becomes restricted to extrasynaptic BL. (c) Likewise, cultured muscles cells restrict 5 and β2 to AChR-rich hot spots but broadly distribute 2 and β1, even in the absence of nerves. (d) Laminin isoforms mark two distinct domains within adult synaptic BL: 2, 5, β2, and 1 are present in both the primary cleft and junctional folds, whereas 4 is restricted to the primary cleft. (e) The endoneurial and perineurial BLs of peripheral nerve each contain distinct laminin chains (2, β2, 1, and 4, 5, β1, 1, respectively). (f) Mutation of the laminin 2 and β2 genes leads to coordinate loss and compensatory upregulation of other chains. (g) Motor axons respond in distinct ways to different laminin heterotrimers: they grow freely between laminin 1 and laminin 2, fail to cross from laminin 4 to laminin 1, and stop upon contacting laminin 11. The ability of laminin 11 to serve as a stop signal for growing axons explains, at least in part, axonal behaviors observed at developing and regenerating synapses in vivo.

Fig. 11 summarizes the main patterns of laminin chain expression that we have documented in muscle. The figure also indicates the heterotrimers (as named in Table I) that we deduce to be present at various stages and sites. This interpretation depends, however, on two assumptions. The first is that all possible β heterotrimers are formed from 1–5, β1, β2, and 1, whenever the constituent chains are present. We know of no evidence against this idea, but it has not been critically tested. The second is that no other laminin chains are present in muscle besides those for which we have probes. In fact, there are some indications that other chains exist. For example, perineurial BL of β2^–/– muscle contains 4 and 1 but little or no β1–3. If all laminins are heterotrimers, there may be another β chain to be discovered in perineurium. Thus, the assignments of trimers made in Fig. 11 and throughout the text must be regarded as provisional.

View larger version (34K): [in this window] [in a new window] [Download PPT slide]   Figure 11 Distribution of laminin chains in synaptic and extrasynaptic BL of developing, adult, and mutant muscle. The diagram summarizes data illustrated in Figs. 1, 3, 4, 6, and 7, and is discussed in the text. Laminins of myotendinous regions were determined for wild type but not mutant muscles. Heterotrimers that could be assembled from the component chains are indicated below each part.

The bioactivity of laminin 11 is consistent with the synaptic defects observed during reinnervation of β2^–/– mutant muscle, in which regenerating axons often extend beyond original synaptic sites (Patton, B.L., and J.R. Sanes, in preparation). However, the coordinate loss of the 5 and β2 chains from mutant synaptic BL raises the question of which chain is responsible for the stopping activity. In support of 5 is the observation that laminin 4 (2/β2/1) does not inhibit neurite outgrowth. In support of β2 is the observation that recombinant β2 fragments exert a potent stopping activity very much like that shown here for native laminin 11 (Porter et al., 1995). One intriguing possibility is that the inhibitory activity resides in the β2 chain, but that it is context dependent, being favored by combination with 5 but opposed by combination with 2.

Recently, Brandenberger et al. (1996) also showed that β2-containing laminin 4 promotes outgrowth of neurites from ciliary neurons and argued against the idea that synaptic laminins serve as stop signals for motor axons. Our results are consistent with theirs, but our new data lead us to question several of their conclusions. First, contrary to their assertion, laminin 4 is not the sole synaptic laminin. Previous findings suggested the existence of at least one additional synaptic laminin (Sanes et al., 1990), and our new results suggest that laminins 4, 9, and 11 are all β2-containing synaptic laminins. Moreover, the phenotypes of the 2^dy/dy and β2^–/– mutants discussed above suggest that laminins 9 and/or 11 are more critical for synaptic function than is laminin 4. Second, based on their finding that laminin 4 does not inhibit neurite outgrowth, Brandenberger et al. (1996) concluded that laminin β2 is unlikely to be involved in the process that leads motor axons to stop growing at synaptic sites. In contrast, our studies of laminin-coated substrates demonstrate that β2-containing laminin 11 is a potent inhibitor of neurite outgrowth. Third, they confirmed our previous reports (Hunter et al., 1989b; Porter et al., 1995) that the tripeptide sequence LRE affects the adhesiveness of a recombinant β2 fragment, and that mutation of this sequence decreases the ability of the fragment to inhibit neurite outgrowth. However, they showed that LRE is inactive when inserted into a recombinant fragment of a chicken cartilage matrix protein, which is predicted to form a coiled-coil structure similar to that of the LRE-containing domain of β2. They therefore argue that the LRE site is unlikely to be active in the native protein. Our results with laminin 11 raise the alternative possibility, that the activity of the LRE site may be context dependent. For example, the juxtaposition of β2 with 5 might disrupt the coiled-coil conformation of the former. Finally, Brandenberger et al. (1996) noted that ciliary neurons extended neurites of the same mean length on substrates of laminins 2 and 4, and therefore concluded that neurite outgrowth on laminin 2 was indistinguishable from that on laminin 4. However, when we observed neurites growing from either laminins 1 and 2 or 1 and 4 onto laminin 1, we found that neurites were blind to laminin 2 but sensitive to laminin 4 borders. Thus, these two trimers do have distinguishable effects on neurites.

We and others have previously documented complex patterns of regulation for the laminins and collagens IV of renal BLs (Kashtan and Kim, 1992; Miner and Sanes, 1994, 1996; Gubler et al., 1995; Noakes et al., 1995b; Cosgrove et al., 1996; Miner et al., 1997). Results presented here extend these phenomena to muscle. First, as in kidney (Miner et al., 1997), individual adult intramuscular BLs can express one (extrasynaptic: 2), two (perineurial: 4+5), or three (synaptic: 2+4+5) chains, along with a single β and chain. Second, the and β chain complements of individual BLs can change as development proceeds. For example, extrasynaptic muscle BL may progress through at least three compositions with regard to its chains (1+2 to 2+5, to 2+4+5, and then to 2). Likewise, in renal glomerular BL, developmental transitions occur in collagen IV chains (1+2 to 1–5, and then to 3–5), laminin chains (1+4 to 1+4+5 to 4+5, and then to 5), and laminin β chains (β1 to β1+2, and then to β2) (Ekblom et al., 1990; Miner and Sanes, 1994; Virtanen et al., 1995; Miner et al., 1997). Third, loss of a single laminin chain from muscle leads to an apparently compensatory appearance of others. For example, decreased expression of 2 in muscle and endoneurial BLs in 2^dy/dy mice leads to increased levels of 4, and loss of β2 from synaptic BL leads to increased levels of β1. These changes are reminiscent of those seen in kidney, where deletion of laminin β2 or collagen IV 3–5 from glomerular BL results in increased levels of laminin β1 or collagen IV 1+2, respectively (Kashtan and Kim, 1992; Noakes et al., 1995b; Cosgrove et al., 1996; Miner and Sanes, 1996). Interestingly, in all of these cases, the compensating chain is one that was normally expressed in embryos and then lost in adults; whether the compensation is best viewed as reexpression or retention of the embryonic phenotype will require further studies of mechanism. Finally, loss of laminin β2 from synaptic and vascular BLs leads to coordinate loss of 5. Likewise, in kidney, mutations in genes encoding any of three collagen IV chains, 3–5, leads to loss of all three chains from glomerular BL (Gubler et al., 1995; Cosgrove et al., 1996; Miner and Sanes, 1996). Together, these results suggest that colocalization of multiple isoforms, isoform transitions during development, and compensation and coregulation in specific deficiency states represent general features of BL assembly and maintenance.

These complexities in composition, development, and regulation are important in considering the roles that laminins play in formation and maintenance of nerve, muscle, and synapse. Potential roles of synaptic laminins are discussed above. As regards muscle, the upregulation or retention of 4 in 2^dy/dy mice may be of particular interest. The 2^dy/dy mouse exhibits severe muscular dystrophy, and has long been used as an animal model of human dystrophies. The recent findings that the 2 gene is mutated both in 2^dy/dy mice and in some humans with congenital dystrophies (Hayashi et al., 1993; Sunada et al., 1994, 1995; Xu et al., 1994b; Helbling-Leclerc et al., 1995; Nissinen et al., 1996) demonstrates that it is a genotypically as well as phenotypically valid model of human disease. In humans with 2 deficiency, levels of another -like chain are increased (Mundegen et al., 1995; Sewry et al., 1995; Connolly et al., 1996); the identity of this chain remains uncertain, but our results suggest that it might be 4. If so, this pattern would resemble that seen in dystrophin-deficient dystrophies (mdx in mice, and Duchenne and Becker in humans), in which utrophin, the autosomal homologue of dystrophin, is expressed transiently in developing normal muscles, but retained or upregulated in adult mutant muscle. Recent studies have shown that utrophin attenuates the severity of dystrophy in mdx mice, and raised the possibility that further upregulation of utrophin could be therapeutically beneficial in humans with Duchenne dystrophy (Tinsley et al., 1996; Deconinck et al., 1997; Grady et al., 1997). Likewise, it will be important to ask whether 4 partially compensates for 2 functionally as well as structurally, and whether it may provide an avenue for intervention in the human disease.

	Acknowledgments

 
We are grateful to Dr. J. Lichtman for advice on confocal imaging, and J. Cunningham, and J. Ko for technical assistance.

This work was supported by grants from the National Institutes of Health. J.H. Miner was supported by a Damon Runyon-Walter Winchell Cancer Research Fund fellowship.

Submitted: 15 August 1997

Revised: 10 October 1997

Address all correspondence to Joshua R. Sanes, Department of Anatomy and Neurobiology, Washington University School of Medicine, 660 South Euclid Avenue, St. Louis, MO 63110. Fax: (314) 747-1150. E-mail: sanesj{at}thalamus.wustl.edu

	References

Top Abstract Materials and Methods Results Discussion References

 

Aberdam D, Aguzzi A, Baudoin C, Galliano MF, Ortonne JP & Meneguzzi G. Developmental expression of nicein adhesion protein (laminin-5) subunits suggests multiple morphogenic roles, Cell Adhes Commun, 1994, 2, 115–129.[Medline]

Abrahamson DR, Irwin MH, St. John PL, Perry EW, Accavitti MA, Heck LW & Couchman JR. Selective immunoreactivities of kidney basement membranes to monoclonal antibodies against laminin: Localization of the end of the long arm and the short arms to discrete microdomains, J Cell Biol, 1989, 109, 3477–3491.[Abstract/Free Full Text]

Arahata K, Hayashi YK, Koga R, Goto K, Lee JH, Miyague Y, Ishii H, Tsukahara T, Takeda S, Woo M et al.. Laminin in animal models for muscular dystrophy: defect of laminin-M in skeletal and cardiac muscles and peripheral nerve of the homozygous dystrophic dy/dy mice, Proc Jpn Acad B, 1993, 69, 259–264.

Banker BQ, Hirst NS, Chester CS & Fok RY. Histometric and electron cytochemical study of muscle in the dystrophic mouse, Ann NY Acad Sci, 1979, 317, 115–131.[Medline]

Bewick GS, Nicholson LVB, Young C, O'Donnell E & Slater CR. Different distributions of dystrophin and related proteins at nerve-muscle junctions, Neuroreport, 1992, 3, 857–860.[Medline]

Brandenberger R, Kammerer RA, Engel J & Chiquet M. Native chick laminin-4 containing the β2 chain (s-laminin) promotes motor axon growth, J Cell Biol, 1996, 135, 1583–1592.[Abstract/Free Full Text]

Bunge MB, Wood PM, Tynan LB, Bates ML & Sanes JR. Perineurium originates from fibroblasts: demonstration in vitro with a retroviral marker, Science, 1989, 243, 229–231.[Abstract/Free Full Text]

Burgeson RE, Chiquet M, Deutzmann R, Ekblom P, Engel J, Kleinman H, Martin GR, Meneguzzi G, Paulsson M, Sanes J et al.. A new nomenclature for the laminins, Matrix Biol, 1994, 14, 209–211.[Medline]

Carbonetto S. Neuromuscular transmission in dystrophic mice, J Neurophysiol, 1977, 40, 836–843.[Abstract/Free Full Text]

Chen, Y.-S., M.F. Champliaud, R.E. Burgeson, M.P. Marenkovich, and P.D. Yurchenco. 1997. Self-assembly of laminin isoforms. J. Biol. Chem. In Press.

Chiu AY & Sanes JR. Development of basal lamina in synaptic and extrasynaptic portions of embryonic rat muscle, Dev Biol, 1984, 103, 456–467.[Medline]

Chiu AY, Ugozolli M, Meiri K & Ko J. Purification and lectin-binding properties of s-laminin, a synaptic isoform of the laminin B1 chain, J Neurochem, 1992, 59, 10–17.[Medline]

Chung AE, Jaffe R, Freeman IL, Vergnes JP, Braginski JE & Carlin B. Properties of a basement membrane-related glycoprotein synthesized in culture by a mouse embryonal carcinoma-derived cell line, Cell, 1979, 16, 277–287.[Medline]

Connolly AM, Pestronk A, Planer GJ, Yue J, Mehta S & Choksi R. Congenital muscular dystrophy syndromes distinguished by alkaline and acid phosphatase, merosin, and dystrophin staining, Neurology, 1996, 46, 810–814.[Free Full Text]

Cosgrove D, Meehan DT, Grunkemeyer JA, Kornak JM, Sayers R, Hunter WJ & Samuelson GC. Collagen COL43 knockout: a mouse model for autosomal Alport syndrome, Genes Dev, 1996, 10, 2981–2992.[Abstract/Free Full Text]

Covault J & Sanes JR. Distribution of N-CAM in synaptic and extrasynaptic portions of developing and adult skeletal muscle, J Cell Biol, 1986, 102, 716–730.[Abstract/Free Full Text]

Covault J, Cunningham JM & Sanes JR. Neurite outgrowth on cryostat sections of innervated and denervated skeletal muscle, J Cell Biol, 1987, 105, 2479–2488.[Abstract/Free Full Text]

Desaki J, Matsuda S & Sakanaka M. Morphological changes of neuromuscular junctions in the dystrophic (dy) mouse: a scanning and transmission electron microscopic study, J Electron Microsc, 1995, 44, 59–65.[Abstract/Free Full Text]

Deconinck, A.E., J.A. Rafael, J.A. Skinner, S.C. Brown, A.C. Potter, L. Metzinger, D.J. Watt, J.G. Dickson, J.M. Tinsley, and K.E. Davies. 1997. Utrophin-dystrophin deficient mice as a model for Duchenne muscular dystrophy. Cell. In press.

Ehrig K, Leivo I, Argraves WS, Ruoslahti E & Engvall E. Merosin, a tissue-specific basement membrane protein, is a laminin-like protein, Proc Natl Acad Sci USA, 1990, 87, 3264–3268.[Abstract/Free Full Text]

Ekblom M, Klein G, Mugrauer G, Fecker L, Deutzmann R, Timpl R & Ekblom P. Transient and locally restricted expression of laminin A chain mRNA by developing epithelial cells during kidney organogenesis, Cell, 1990, 60, 337–346.[Medline]

Engvall E, Earwicker D, Haaparanta T, Ruoslahti E & Sanes JR. Distribution and isolation of four laminin variants; tissue restricted distribution of heterotrimers assembled from five different subunits, Cell Regul, 1990, 1, 731–740.[Medline]

Ferns MJ, Campanelli JT, Hoch W, Scheller RH & Hall Z. The ability of agrin to cluster AChRs depends on alternative splicing and on cell surface proteoglycans, Neuron, 1993, 11, 491–502.[Medline]

Fertuck HC & Salpeter MM. Quantitation of junctional and extrajunctional acetylcholine receptors by electron microscope autoradiography after ¹²⁵I--bungarotoxin binding at mouse neuromuscular junctions, J Cell Biol, 1976, 69, 144–158.[Abstract/Free Full Text]

Flucher BE & Daniels MP. Distribution of Na⁺channels and ankyrin in neuromuscular junctions is complementary to that of acetylcholine receptors and the 43 kd protein, Neuron, 1989, 3, 163–175.[Medline]

Grady RM, Teng H, Nichol MC, Cunningham JC, Wilkinson RS & Sanes JR. Skeletal and cardiac myopathies in mice lacking utrophin and dystrophin: a model for Duchenne muscular dystrophy, Cell, 1997, 90, 729–738.[Medline]

Green TL, Hunter DD, Chan W, Merlie JP & Sanes JR. Synthesis and assembly of the synaptic cleft protein S-laminin by cultured cells, J Biol Chem, 1992, 267, 2014–2022.[Abstract/Free Full Text]

Gubler M-C, Knebelmann B, Beziau A, Broyer M, Pirson Y, Haddoum F, Kleppel MM & Antignac C. Autosomal recessive Alport syndrome: immunohistochemical study of type IV collagen chain distribution, Kidney Int, 1995, 47, 1142–1147.[Medline]

Hayashi YK, Engvall E, Arikawa HE, Goto K, Koga R, Nonaka I, Sugita H & Arahata K. Abnormal localization of laminin subunits in muscular dystrophies, J Neurol Sci, 1993, 119, 53–64.[Medline]

Helbling-Leclerc A, Zhang X, Topaloglu H, Cruaud C, Tesson F, Weissenbach J, Tome FM, Schwartz K, Fardeau M, Tryggvason K et al.. Mutations in the laminin 2-chain gene (LAMA2) cause merosin-deficient congenital muscular dystrophy, Nat Genet, 1995, 11, 216–218.[Medline]

Hunter DD, Shah V, Merlie JP & Sanes JR. A laminin-like adhesive protein concentrated in the synaptic cleft of the neuromuscular junction, Nature, 1989a, 338, 229–234.[Medline]

Hunter DD, Porter BE, Bulock JW, Adams SP, Merlie JP & Sanes JR. Primary sequence of a motor neuron-selective adhesive site in the synaptic basal lamina protein S-laminin, Cell, 1989b, 59, 905–913.[Medline]

Jaakkola S, Savunen O, Halme T, Uitto J & Peltonen J. Basement membranes during development of human nerve: Schwann cells and perineurial cells display marked changes in their expression profiles for laminin subunits and β1 and β4 integrins, J Neurocytol, 1993, 22, 215–230.[Medline]

Kashtan CE & Kim Y. Distribution of the 1 and 2-chains of collagen IV and of collagens V and VI in Alport syndrome, Kidney Int, 1992, 42, 115–126.[Medline]

Kelly AM & Zacks SI. The histogenesis of rat intercostal muscle, J Cell Biol, 1969a, 42, 135–153.[Abstract/Free Full Text]

Kelly AM & Zacks SI. The fine structure of motor endplate morphogenesis, J Cell Biol, 1969b, 42, 154–169.[Abstract/Free Full Text]

Kroll TG, Peters BP, Hustad CM, Jones PA, Killen PD & Ruddon RW. Expression of laminin chains during myogenic differentiation, J Biol Chem, 1994, 269, 9270–9277.[Abstract/Free Full Text]

Lagenaur C & Lemmon V. An L1-like molecule, the 8D9 antigen, is a potent substrate for neurite extension, Proc Natl Acad Sci USA, 1987, 84, 7753–7757.[Abstract/Free Full Text]

Law PK, Saito A & Fleischer S. Ultrastructural changes in muscle and motor end-plates of the dystrophic mouse, Exp Neurol, 1983, 80, 361–382.[Medline]

Leivo I & Engvall E. Merosin, a protein specific for basement membranes of Schwann cells, striated muscle, and trophoblast, is expressed late in nerve and muscle development, Proc Natl Acad Sci USA, 1988, 85, 1544–1548.[Abstract/Free Full Text]

Marinkovich MP, Lunstrum GP & Burgeson RE. The anchoring filament protein kalinin is synthesized and secreted as a high molecular weight precursor, J Biol Chem, 1992, 267, 17900–17906.[Abstract/Free Full Text]

Martin PT, Ettinger AJ & Sanes JR. A synaptic localization domain in the synaptic cleft protein laminin β2 (s-laminin), Science, 1995, 269, 413–416.[Abstract/Free Full Text]

Merrill GF. Clonal derivation of a rat muscle cell strain that forms contraction-competent myotubes, In Vitro Cell Dev Biol, 1989, 25, 471–476.[Medline]

Miner JH & Sanes JR. Collagen IV 3, 4, and 5 chains in rodent basal laminae: Sequence, distribution, association with laminins, and developmental switches, J Cell Biol, 1994, 127, 879–891.[Abstract/Free Full Text]

Miner JH & Sanes JR. Molecular and functional defects in kidneys of mice lacking collagen (3)IV: Implications for alport syndrome, J Cell Biol, 1996, 135, 1403–1413.[Abstract/Free Full Text]

Miner JH, Patton BL, Lentz SI, Gilbert DJ, Snider WD, Jenkins NA, Copeland NG & Sanes JR. The laminin chains: Expression, developmental transitions, and chromosomal locations of 1-5, identification of heterotrimeric laminins 8-11, and cloning of a novel 3 isoform, J Cell Biol, 1997, 137, 685–701.[Abstract/Free Full Text]

Mundegar RR, von Oertzen J & Zierz S. Increased laminin A expression in regenerating myofibers in neuromuscular disorders, Muscle & Nerve, 1995, 18, 992–999.[Medline]

Nishi R & Berg DK. Two components from eye tissue that differentially stimulate the growth and development of ciliary ganglion neurons in cell culture, J Neurosci, 1981, 1, 505–513.[Abstract]

Nissinen M, Helbling LA, Zhang X, Evangelista T, Topaloglu H, Cruaud C, Weissenbach J, Fardeau M, Tome FM, Schwartz K et al.. Substitution of a conserved cysteine-996 in a cysteine-rich motif of the laminin 2-chain in congenital muscular dystrophy with partial deficiency of the protein, Am J Hum Genet, 1996, 58, 1177–1184.[Medline]

Noakes PG, Phillips WD, Hanley TA, Sanes JR & Merlie JP. 43K protein and acetylcholine receptors colocalize during the initial stages of neuromuscular synapse formation in vivo, Dev Biol, 1993, 155, 275–280.[Medline]

Noakes PG, Gautam M, Mudd J, Sanes JR & Merlie JP. Aberrant differentiation of neuromuscular junctions in mice lacking s-laminin/ laminin β2, Nature, 1995a, 374, 258–262.[Medline]

Noakes PG, Miner JH, Gautam M, Cunningham JM, Sanes JR & Merlie JP. The renal glomerulus of mice lacking s-laminin/laminin β2: nephrosis despite molecular compensation by laminin β1, Nat Genet, 1995b, 10, 400–406.[Medline]

Porter BE & Sanes JR. Gated migration: neurons migrate on but not onto substrates containing S-laminin, Dev Biol, 1995, 167, 609–616.[Medline]

Porter BE, Weis J & Sanes JR. A motoneuron-selective stop signal in the synaptic cleft protein S-laminin, Neuron, 1995, 14, 549–559.[Medline]

Rosen GD, Sanes JR, LaChance R, Cunningham JM, Roman J & Dean DC. Roles for the integrin VLA-4 and its counter receptor VCAM-1 in myogenesis, Cell, 1992, 69, 1107–1119.[Medline]

Sanes, J.R. 1994. The extracellular matrix. In Myology. 2nd edition, A.G. Engel, and C. Franzini-Armstrong, editors. McGraw-Hill Inc., New York. 242– 260.

Sanes JR. The synaptic cleft of the neuromuscular junction, Semin Dev Biol, 1995, 6, 163–173.

Sanes JR & Chiu AY. The basal lamina of the neuromuscular junction, Cold Spring Harbor Symp Quant Biol, 1983, 48, 667–678.[Abstract/Free Full Text]

Sanes JR & Lawrence JJ. Activity-dependent accumulation of basal lamina by cultured rat myotubes, Dev Biol, 1983, 97, 123–136.[Medline]

Sanes JR, Marshall LM & McMahan UJ. Reinnervation of muscle fiber basal lamina after removal of myofibers. Differentiation of regenerating axons at original synaptic sites, J Cell Biol, 1978, 78, 176–198.[Abstract/Free Full Text]

Sanes JR, Schachner M & Covault J. Expression of several adhesive macromolecules (N-CAM, L1, J1, NILE, uvomorulin, laminin, fibronectin, and a heparan sulfate proteoglycan) in embryonic, adult, and denervated adult skeletal muscle, J Cell Biol, 1986, 102, 420–431.[Abstract/Free Full Text]

Sanes JR, Engvall E, Butkowski R & Hunter DD. Molecular heterogeneity of basal laminae: Isoforms of laminin and collagen IV at the neuromuscular junction and elsewhere, J Cell Biol, 1990, 111, 1685–1699.[Abstract/Free Full Text]

Schuler F & Sorokin LM. Expression of laminin isoforms in mouse myogenic cells in vitro and in vivo, J Cell Sci, 1995, 108, 3795–3805.[Abstract]

Sewry CA, Philpot J, Mahony D, Wilson LA, Muntoni F & Dubowitz V. Expression of laminin subunits in congenital muscular dystrophy, Neuromuscul Disord, 1995, 5, 307–316.[Medline]

Silberstein L, Inestrosa NC & Hall ZW. Aneural muscle cell cultures make synaptic basal lamina components, Nature, 1982, 295, 143–145.[Medline]

Sorokin LM, Conzelmann S, Ekblom P, Battaglia C, Aumailley M & Timpl R. Monoclonal antibodies against laminin A chain fragment E3 and their effects on binding to cells and proteoglycan and on kidney development, Exp Cell Res, 1992, 201, 137–144.[Medline]

Sunada Y, Bernier SM, Kozak CA, Yamada Y & Campbell KP. Deficiency of merosin in dystrophic dy mice and genetic linkage of laminin M chain gene to dy locus, J Biol Chem, 1994, 269, 13729–13732.[Abstract/Free Full Text]

Sunada Y, Bernier SM, Utani A, Yamada Y & Campbell KP. Identification of a novel mutant transcript of laminin 2 chain gene responsible for muscular dystrophy and dysmyelination in dy2J mice, Hum Mol Genet, 1995, 4, 1055–1061.[Free Full Text]

Timpl R, Rohde H, Robey PG, Rennard SI, Foidart JM & Martin GR. Laminin—a glycoprotein from basement membranes, J Biol Chem, 1979, 254, 9933–9937.[Abstract/Free Full Text]

Tinsley JM, Potter AC, Phelps SR, Fisher R, Trickett JI & Davies KE. Amelioration of the dystrophic phenotype of mdxmice using a truncated utrophin transgene, Nature, 1996, 384, 349–353.[Medline]

Vachon PH, Loechel F, Xu H, Wewer UM & Engvall E. Merosin and laminin in myogenesis; specific requirement for merosin in myotube stability and survival, J Cell Biol, 1996, 134, 1483–1497.[Abstract/Free Full Text]

Virtanen I, Laitinen L & Korhonen M. Differential expression of laminin polypeptides in developing and adult human kidney, J Histochem Cytochem, 1995, 43, 621–628.[Abstract]

Virtanen I, Laitinen A, Tani T, Paakko P, Laitinen LA, Burgeson RE & Lehto VP. Differential expression of laminins and their integrin receptors in developing and adult human lung, Am J Respir Cell Mol Biol, 1996, 15, 184–196.[Abstract]

Weaver CD, Yoshida CK, de Curtis I & Reichardt LF. Expression and in vitro function of β₁-integrin laminin receptors in the developing avian ciliary ganglion, J Neurosci, 1995, 15, 5275–5285.[Abstract]

Xu H, Christmas P, Wu XR, Wewer UM & Engvall E. Defective muscle basement membrane and lack of M-laminin in the dystrophic dy/dy mouse, Proc Natl Acad Sci USA, 1994a, 91, 5572–5576.[Abstract/Free Full Text]

Xu H, Wu XR, Wewer UM & Engvall E. Murine muscular dystrophy caused by a mutation in the laminin 2 (Lama2) gene, Nat Genet, 1994b, 8, 297–302.[Medline]

Zhang M & McLennan IS. During secondary myotube formation, primary myotubes preferentially absorb new nuclei at their ends, Dev Dyn, 1995, 204, 168–177.[Medline]

CiteULike

Complore

Connotea

Del.icio.us

Digg

Facebook

Reddit

Technorati

Twitter

This article has been cited by other articles:

• Proszynski, T. J., Gingras, J., Valdez, G., Krzewski, K., Sanes, J. R. (2009). Podosomes are present in a postsynaptic apparatus and participate in its maturation. Proc. Natl. Acad. Sci. USA 106: 18373-18378 [Abstract] [Full Text]  
• Sime, W., Lunderius-Andersson, C., Enoksson, M., Rousselle, P., Tryggvason, K., Nilsson, G., Harvima, I., Patarroyo, M. (2009). Human Mast Cells Adhere to and Migrate on Epithelial and Vascular Basement Membrane Laminins LM-332 and LM-511 via {alpha}3{beta}1 Integrin. J. Immunol. 183: 4657-4665 [Abstract] [Full Text]  
• Relucio, J., Tzvetanova, I. D., Ao, W., Lindquist, S., Colognato, H. (2009). Laminin Alters Fyn Regulatory Mechanisms and Promotes Oligodendrocyte Development. J. Neurosci. 29: 11794-11806 [Abstract] [Full Text]  
• Wang, Z., Wang, B., Yang, L., Guo, Q., Aithmitti, N., Songyang, Z., Zheng, H. (2009). Presynaptic and Postsynaptic Interaction of the Amyloid Precursor Protein Promotes Peripheral and Central Synaptogenesis. J. Neurosci. 29: 10788-10801 [Abstract] [Full Text]  
• McKee, K. K., Capizzi, S., Yurchenco, P. D. (2009). Scaffold-forming and Adhesive Contributions of Synthetic Laminin-binding Proteins to Basement Membrane Assembly. J. Biol. Chem. 284: 8984-8994 [Abstract] [Full Text]  
• Court, F. A., Hewitt, J. E., Davies, K., Patton, B. L., Uncini, A., Wrabetz, L., Feltri, M. L. (2009). A Laminin-2, Dystroglycan, Utrophin Axis Is Required for Compartmentalization and Elongation of Myelin Segments. J. Neurosci. 29: 3908-3919 [Abstract] [Full Text]  
• Taniguchi, Y., Ido, H., Sanzen, N., Hayashi, M., Sato-Nishiuchi, R., Futaki, S., Sekiguchi, K. (2009). The C-terminal Region of Laminin {beta} Chains Modulates the Integrin Binding Affinities of Laminins. J. Biol. Chem. 284: 7820-7831 [Abstract] [Full Text]  
• Rooney, J. E., Gurpur, P. B., Yablonka-Reuveni, Z., Burkin, D. J. (2009). Laminin-111 Restores Regenerative Capacity in a Mouse Model for {alpha}7 Integrin Congenital Myopathy. Am. J. Pathol. 174: 256-264 [Abstract] [Full Text]  
• Nishimune, H., Valdez, G., Jarad, G., Moulson, C. L., Muller, U., Miner, J. H., Sanes, J. R. (2008). Laminins promote postsynaptic maturation by an autocrine mechanism at the neuromuscular junction. JCB 182: 1201-1215 [Abstract] [Full Text]  
• Patton, B. L., Wang, B., Tarumi, Y. S., Seburn, K. L., Burgess, R. W. (2008). A single point mutation in the LN domain of LAMA2 causes muscular dystrophy and peripheral amyelination. J. Cell Sci. 121: 1593-1604 [Abstract] [Full Text]  
• Jakobsson, L., Domogatskaya, A., Tryggvason, K., Edgar, D., Claesson-Welsh, L. (2008). Laminin deposition is dispensable for vasculogenesis but regulates blood vessel diameter independent of flow. FASEB J. 22: 1530-1539 [Abstract] [Full Text]  
• Sann, S. B., Xu, L., Nishimune, H., Sanes, J. R., Spitzer, N. C. (2008). Neurite Outgrowth and In Vivo Sensory Innervation Mediated by a CaV2.2-Laminin {beta}2 Stop Signal. J. Neurosci. 28: 2366-2374 [Abstract] [Full Text]  
• LeBleu, V. S., MacDonald, B., Kalluri, R. (2007). Structure and Function of Basement Membranes. Exp. Biol. Med. 232: 1121-1129 [Abstract] [Full Text]  
• Xu, R., Chandrasekharan, K., Yoon, J. H., Camboni, M., Martin, P. T. (2007). Overexpression of the Cytotoxic T Cell (CT) Carbohydrate Inhibits Muscular Dystrophy in the dyW Mouse Model of Congenital Muscular Dystrophy 1A. Am. J. Pathol. 171: 181-199 [Abstract] [Full Text]  
• Meinen, S., Barzaghi, P., Lin, S., Lochmuller, H., Ruegg, M. A. (2007). Linker molecules between laminins and dystroglycan ameliorate laminin-{alpha}2-deficient muscular dystrophy at all disease stages. JCB 176: 979-993 [Abstract] [Full Text]  
• Weston, C. A., Teressa, G., Weeks, B. S., Prives, J. (2007). Agrin and laminin induce acetylcholine receptor clustering by convergent, Rho GTPase-dependent signaling pathways. J. Cell Sci. 120: 868-875 [Abstract] [Full Text]  
• Triolo, D., Dina, G., Lorenzetti, I., Malaguti, M., Morana, P., Del Carro, U., Comi, G., Messing, A., Quattrini, A., Previtali, S. C. (2006). Loss of glial fibrillary acidic protein (GFAP) impairs Schwann cell proliferation and delays nerve regeneration after damage.. J. Cell Sci. 119: 3981-3993 [Abstract] [Full Text]  
• Gawlik, K. I., Li, J.-Y., Petersen, A., Durbeej, M. (2006). Laminin {alpha}1 chain improves laminin {alpha}2 chain deficient peripheral neuropathy. Hum Mol Genet 15: 2690-2700 [Abstract] [Full Text]  
• Tremblay, M. R., Carbonetto, S. (2006). An Extracellular Pathway for Dystroglycan Function in Acetylcholine Receptor Aggregation and Laminin Deposition in Skeletal Myotubes. J. Biol. Chem. 281: 13365-13373 [Abstract] [Full Text]  
• van Lunteren, E., Moyer, M., Leahy, P. (2006). Gene expression profiling of diaphragm muscle in {alpha}2-laminin (merosin)-deficient dy/dy dystrophic mice. Physiol. Genomics 25: 85-95 [Abstract] [Full Text]  
• Eremina, V., Cui, S., Gerber, H., Ferrara, N., Haigh, J., Nagy, A., Ema, M., Rossant, J., Jothy, S., Miner, J. H., Quaggin, S. E. (2006). Vascular Endothelial Growth Factor A Signaling in the Podocyte-Endothelial Compartment Is Required for Mesangial Cell Migration and Survival. J. Am. Soc. Nephrol. 17: 724-735 [Abstract] [Full Text]  
• Miner, J. H., Go, G., Cunningham, J., Patton, B. L., Jarad, G. (2006). Transgenic isolation of skeletal muscle and kidney defects in laminin {beta}2 mutant mice: implications for Pierson syndrome. Development 133: 967-975 [Abstract] [Full Text]  
• Fukumoto, S., Miner, J. H., Ida, H., Fukumoto, E., Yuasa, K., Miyazaki, H., Hoffman, M. P., Yamada, Y. (2006). Laminin {alpha}5 Is Required for Dental Epithelium Growth and Polarity and the Development of Tooth Bud and Shape. J. Biol. Chem. 281: 5008-5016 [Abstract] [Full Text]  
• Wang, J., Hoshijima, M., Lam, J., Zhou, Z., Jokiel, A., Dalton, N. D., Hultenby, K., Ruiz-Lozano, P., Ross, J. Jr., Tryggvason, K., Chien, K. R. (2006). Cardiomyopathy Associated with Microcirculation Dysfunction in Laminin {alpha}4 Chain-deficient Mice. J. Biol. Chem. 281: 213-220 [Abstract] [Full Text]  
• Occhi, S., Zambroni, D., Del Carro, U., Amadio, S., Sirkowski, E. E., Scherer, S. S., Campbell, K. P., Moore, S. A., Chen, Z.-L., Strickland, S., Di Muzio, A., Uncini, A., Wrabetz, L., Feltri, M. L. (2005). Both Laminin and Schwann Cell Dystroglycan Are Necessary for Proper Clustering of Sodium Channels at Nodes of Ranvier. J. Neurosci. 25: 9418-9427 [Abstract] [Full Text]  
• Hata, D., Miyazaki, M., Seto, S., Kadota, E., Muso, E., Takasu, K., Nakano, A., Tamai, K., Uitto, J., Nagata, M., Moriyama, K., Miyazaki, K. (2005). Nephrotic Syndrome and Aberrant Expression of Laminin Isoforms in Glomerular Basement Membranes for an Infant With Herlitz Junctional Epidermolysis Bullosa. Pediatrics 116: e601-e607 [Abstract] [Full Text]  
• Qiao, C., Li, J., Zhu, T., Draviam, R., Watkins, S., Ye, X., Chen, C., Li, J., Xiao, X. (2005). Amelioration of laminin-{alpha}2-deficient congenital muscular dystrophy by somatic gene transfer of miniagrin. Proc. Natl. Acad. Sci. USA 102: 11999-12004 [Abstract] [Full Text]  
• Bentzinger, C. F., Barzaghi, P., Lin, S., Ruegg, M. A. (2005). Overexpression of mini-agrin in skeletal muscle increases muscle integrity and regenerative capacity in laminin-{alpha}2-deficient mice. FASEB J. 19: 934-942 [Abstract] [Full Text]  
• Yu, W.-M., Feltri, M. L., Wrabetz, L., Strickland, S., Chen, Z.-L. (2005). Schwann Cell-Specific Ablation of Laminin {gamma}1 Causes Apoptosis and Prevents Proliferation. J. Neurosci. 25: 4463-4472 [Abstract] [Full Text]  
• Kishi, M., Kummer, T. T., Eglen, S. J., Sanes, J. R. (2005). LL5{beta}: a regulator of postsynaptic differentiation identified in a screen for synaptically enriched transcripts at the neuromuscular junction. JCB 169: 355-366 [Abstract] [Full Text]  
• Yang, D., Bierman, J., Tarumi, Y. S., Zhong, Y.-P., Rangwala, R., Proctor, T. M., Miyagoe-Suzuki, Y., Takeda, S., Miner, J. H., Sherman, L. S., Gold, B. G., Patton, B. L. (2005). Coordinate control of axon defasciculation and myelination by laminin-2 and -8. JCB 168: 655-666 [Abstract] [Full Text]  
• Kjellgren, D., Thornell, L.-E., Virtanen, I., Pedrosa-Domellof, F. (2004). Laminin Isoforms in Human Extraocular Muscles. IOVS 45: 4233-4239 [Abstract] [Full Text]  
• Dixelius, J., Jakobsson, L., Genersch, E., Bohman, S., Ekblom, P., Claesson-Welsh, L. (2004). Laminin-1 Promotes Angiogenesis in Synergy with Fibroblast Growth Factor by Distinct Regulation of the Gene and Protein Expression Profile in Endothelial Cells. J. Biol. Chem. 279: 23766-23772 [Abstract] [Full Text]  
• Yuasa, K., Fukumoto, S., Kamasaki, Y., Yamada, A., Fukumoto, E., Kanaoka, K., Saito, K., Harada, H., Arikawa-Hirasawa, E., Miyagoe-Suzuki, Y., Takeda, S., Okamoto, K., Kato, Y., Fujiwara, T. (2004). Laminin {alpha}2 Is Essential for Odontoblast Differentiation Regulating Dentin Sialoprotein Expression. J. Biol. Chem. 279: 10286-10292 [Abstract] [Full Text]  
• Hoyte, K., Jayasinha, V., Xia, B., Martin, P. T. (2004). Transgenic Overexpression of Dystroglycan Does Not Inhibit Muscular Dystrophy in mdx Mice. Am. J. Pathol. 164: 711-718 [Abstract] [Full Text]  
• Martin, P. T. (2003). Dystroglycan glycosylation and its role in matrix binding in skeletal muscle. Glycobiology 13: 55R-66R [Abstract] [Full Text]  
• Previtali, S. C., Nodari, A., Taveggia, C., Pardini, C., Dina, G., Villa, A., Wrabetz, L., Quattrini, A., Feltri, M. L. (2003). Expression of Laminin Receptors in Schwann Cell Differentiation: Evidence for Distinct Roles. J. Neurosci. 23: 5520-5530 [Abstract] [Full Text]  
• Mayer, U. (2003). Integrins: Redundant or Important Players in Skeletal Muscle?. J. Biol. Chem. 278: 14587-14590 [Full Text]  
• Sanes, J. R. (2003). The Basement Membrane/Basal Lamina of Skeletal Muscle. J. Biol. Chem. 278: 12601-12604 [Full Text]  
• Guan, W., Puthenveedu, M. A., Condic, M. L. (2003). Sensory Neuron Subtypes Have Unique Substratum Preference and Receptor Expression before Target Innervation. J. Neurosci. 23: 1781-1791 [Abstract] [Full Text]  
• Knight, D., Tolley, L. K, Kim, D. K, Lavidis, N. A, Noakes, P. G (2003). Functional analysis of neurotransmission at {beta}2-laminin deficient terminals. J. Physiol. 546: 789-800 [Abstract] [Full Text]  
• Kikkawa, Y., Moulson, C. L., Virtanen, I., Miner, J. H. (2002). Identification of the Binding Site for the Lutheran Blood Group Glycoprotein on Laminin alpha 5 through Expression of Chimeric Laminin Chains in Vivo. J. Biol. Chem. 277: 44864-44869 [Abstract] [Full Text]  
• Marangi, P. A., Wieland, S. T., Fuhrer, C. (2002). Laminin-1 redistributes postsynaptic proteins and requires rapsyn, tyrosine phosphorylation, and Src and Fyn to stably cluster acetylcholine receptors. JCB 157: 883-895 [Abstract] [Full Text]  
• Smirnov, S. P., McDearmon, E. L., Li, S., Ervasti, J. M., Tryggvason, K., Yurchenco, P. D. (2002). Contributions of the LG Modules and Furin Processing to Laminin-2 Functions. J. Biol. Chem. 277: 18928-18937 [Abstract] [Full Text]  
• Grimpe, B., Dong, S., Doller, C., Temple, K., Malouf, A. T., Silver, J. (2002). The Critical Role of Basement Membrane-Independent Laminin gamma 1 Chain during Axon Regeneration in the CNS. J. Neurosci. 22: 3144-3160 [Abstract] [Full Text]  
• Doi, M., Thyboll, J., Kortesmaa, J., Jansson, K., Iivanainen, A., Parvardeh, M., Timpl, R., Hedin, U., Swedenborg, J., Tryggvason, K. (2002). Recombinant Human Laminin-10 (alpha 5beta 1gamma 1). PRODUCTION, PURIFICATION, AND MIGRATION-PROMOTING ACTIVITY ON VASCULAR ENDOTHELIAL CELLS. J. Biol. Chem. 277: 12741-12748 [Abstract] [Full Text]  
• Erdman, R., Stahl, R. C., Rothblum, K., Chernousov, M. A., Carey, D. J. (2002). Schwann Cell Adhesion to a Novel Heparan Sulfate Binding Site in the N-terminal Domain of alpha 4 Type V Collagen Is Mediated by Syndecan-3. J. Biol. Chem. 277: 7619-7625 [Abstract] [Full Text]  
• Thyboll, J., Kortesmaa, J., Cao, R., Soininen, R., Wang, L., Iivanainen, A., Sorokin, L., Risling, M., Cao, Y., Tryggvason, K. (2002). Deletion of the Laminin {alpha}4 Chain Leads to Impaired Microvessel Maturation. Mol. Cell. Biol. 22: 1194-1202 [Abstract] [Full Text]  
• von der Mark, H., Williams, I., Wendler, O., Sorokin, L., von der Mark, K., Poschl, E. (2002). Alternative Splice Variants of alpha 7beta 1 Integrin Selectively Recognize Different Laminin Isoforms. J. Biol. Chem. 277: 6012-6016 [Abstract] [Full Text]  
• Tsiper, M. V., Yurchenco, P. D. (2002). Laminin assembles into separate basement membrane and fibrillar matrices in Schwann cells. J. Cell Sci. 115: 1005-1015 [Abstract] [Full Text]  
• Schreider, C., Peignon, G., Thenet, S., Chambaz, J., Pincon-Raymond, M. (2002). Integrin-mediated functional polarization of Caco-2 cells through E-cadherin--actin complexes. J. Cell Sci. 115: 543-552 [Abstract] [Full Text]  
• Bonner, J., O'Connor, T. P. (2001). The Permissive Cue Laminin Is Essential for Growth Cone Turning In Vivo. J. Neurosci. 21: 9782-9791 [Abstract] [Full Text]  
• Li, X., Talts, U., Talts, J. F., Arman, E., Ekblom, P., Lonai, P. (2001). Akt/PKB regulates laminin and collagen IV isotypes of the basement membrane. Proc. Natl. Acad. Sci. USA 98: 14416-14421 [Abstract] [Full Text]  
• Chernousov, M. A., Stahl, R. C., Carey, D. J. (2001). Schwann Cell Type V Collagen Inhibits Axonal Outgrowth and Promotes Schwann Cell Migration via Distinct Adhesive Activities of the Collagen and Noncollagen Domains. J. Neurosci. 21: 6125-6135 [Abstract] [Full Text]  
• Sixt, M., Engelhardt, B., Pausch, F., Hallmann, R., Wendler, O., Sorokin, L. M. (2001). Endothelial Cell Laminin Isoforms, Laminins 8 and 10, Play Decisive Roles in T Cell Recruitment across the Blood-Brain Barrier in Experimental Autoimmune Encephalomyelitis. JCB 153: 933-946 [Abstract] [Full Text]  
• Smith, C. L., Mittaud, P., Prescott, E. D., Fuhrer, C., Burden, S. J. (2001). Src, Fyn, and Yes Are Not Required for Neuromuscular Synapse Formation But Are Necessary for Stabilization of Agrin-Induced Clusters of Acetylcholine Receptors. J. Neurosci. 21: 3151-3160 [Abstract] [Full Text]  
• Hao, J., Jackson, L., Calaluce, R., McDaniel, K., Dalkin, B. L., Nagle, R. B. (2001). Investigation into the Mechanism of the Loss of Laminin 5 ({{alpha}}3{beta}3{{gamma}}2) Expression in Prostate Cancer. Am. J. Pathol. 158: 1129-1135 [Abstract] [Full Text]  
• Spessotto, P., Yin, Z., Magro, G., Deutzmann, R., Chiu, A., Colombatti, A., Perris, R. (2001). Laminin Isoforms 8 and 10 Are Primary Components of the Subendothelial Basement Membrane Promoting Interaction with Neoplastic Lymphocytes. Cancer Res. 61: 339-347 [Abstract] [Full Text]  
• Cosgrove, D., Rodgers, K., Meehan, D., Miller, C., Bovard, K., Gilroy, A., Gardner, H., Kotelianski, V., Gotwals, P., Amatucci, A., Kalluri, R. (2000). Integrin {alpha}1{beta}1 and Transforming Growth Factor-{beta}1 Play Distinct Roles in Alport Glomerular Pathogenesis and Serve as Dual Targets for Metabolic Therapy. Am. J. Pathol. 157: 1649-1659 [Abstract] [Full Text]  
• Pegoraro, E., Fanin, M., Trevisan, C. P., Angelini, C., Hoffman, E. P. (2000). A novel laminin {alpha}2 isoform in severe laminin {alpha}2 deficient congenital muscular dystrophy. Neurology 55: 1128-1134 [Abstract] [Full Text]  
• Rafuse, V. F., Polo-Parada, L., Landmesser, L. T. (2000). Structural and Functional Alterations of Neuromuscular Junctions in NCAM-Deficient Mice. J. Neurosci. 20: 6529-6539 [Abstract] [Full Text]  
• Briguet, A., Ruegg, M. A. (2000). The Ets Transcription Factor GABP Is Required for Postsynaptic Differentiation In Vivo. J. Neurosci. 20: 5989-5996 [Abstract] [Full Text]  
• Nguyen, Q. T., Son, Y.-J., Sanes, J. R., Lichtman, J. W. (2000). Nerve Terminals Form But Fail to Mature When Postsynaptic Differentiation Is Blocked: In Vivo Analysis Using Mammalian Nerve-Muscle Chimeras. J. Neurosci. 20: 6077-6086 [Abstract] [Full Text]  
• Cohen, M. W., Hoffstrom, B. G., DeSimone, D. W. (2000). Active Zones on Motor Nerve Terminals Contain alpha 3beta 1 Integrin. J. Neurosci. 20: 4912-4921 [Abstract] [Full Text]  
• Jenniskens, G. J., Oosterhof, A., Brandwijk, R., Veerkamp, J. H., van Kuppevelt, T. H. (2000). Heparan Sulfate Heterogeneity in Skeletal Muscle Basal Lamina: Demonstration by Phage Display-Derived Antibodies. J. Neurosci. 20: 4099-4111 [Abstract] [Full Text]  
• Kortesmaa, J., Yurchenco, P., Tryggvason, K. (2000). Recombinant Laminin-8 (alpha 4beta 1gamma 1). PRODUCTION, PURIFICATION, AND INTERACTIONS WITH INTEGRINS. J. Biol. Chem. 275: 14853-14859 [Abstract] [Full Text]  
• Nielsen, P. K., Gho, Y. S., Hoffman, M. P., Watanabe, H., Makino, M., Nomizu, M., Yamada, Y. (2000). Identification of a Major Heparin and Cell Binding Site in the LG4 Module of the Laminin alpha 5 Chain. J. Biol. Chem. 275: 14517-14523 [Abstract] [Full Text]  
• Pedrosa–Domellöf, F., Tiger, C.-F., Virtanen, I., Thornell, L.-E., Gullberg, D. (2000). Laminin Chains in Developing and Adult Human Myotendinous Junctions. J. Histochem. Cytochem. 48: 201-210 [Abstract] [Full Text]  
• Sunderland, W. J., Son, Y.-J., Miner, J. H., Sanes, J. R., Carlson, S. S. (2000). The Presynaptic Calcium Channel Is Part of a Transmembrane Complex Linking a Synaptic Laminin (alpha 4beta 2gamma 1) with Non-Erythroid Spectrin. J. Neurosci. 20: 1009-1019 [Abstract] [Full Text]  
• Burkin, D., Kim, J., Gu, M, Kaufman, S. (2000). Laminin and alpha7beta1 integrin regulate agrin-induced clustering of acetylcholine receptors. J. Cell Sci. 113: 2877-2886 [Abstract]  
• Son, Y.-J., Scranton, T. W., Sunderland, W. J., Baek, S. J., Miner, J. H., Sanes, J. R., Carlson, S. S. (2000). The Synaptic Vesicle Protein SV2 Is Complexed with an alpha 5-Containing Laminin on the Nerve Terminal Surface. J. Biol. Chem. 275: 451-460 [Abstract] [Full Text]  
• Relan, N. K., Yang, Y., Beqaj, S., Miner, J. H., Schuger, L. (1999). Cell Elongation Induces Laminin {alpha}2 Chain Expression in Mouse Embryonic Mesenchymal Cells: Role in Visceral Myogenesis. JCB 147: 1341-1350 [Abstract] [Full Text]  
• Nagaoka, T., Oyamada, M., Okajima, S., Takamatsu, T. (1999). Differential Expression of Gap Junction Proteins Connexin26, 32, and 43 in Normal and Crush-injured Rat Sciatic Nerves: Close Relationship Between Connexin43 and Occludin in the Perineurium. J. Histochem. Cytochem. 47: 937-948 [Abstract] [Full Text]  
• Montanaro, F., Lindenbaum, M., Carbonetto, S. (1999). {alpha}-Dystroglycan Is a Laminin Receptor Involved in Extracellular Matrix Assembly on Myotubes and Muscle Cell Viability. JCB 145: 1325-1340 [Abstract] [Full Text]  
• Colognato, H., Winkelmann, D. A., Yurchenco, P. D. (1999). Laminin Polymerization Induces a Receptor-Cytoskeleton Network. JCB 145: 619-631 [Abstract] [Full Text]  
• Jones, G., Moore, C., Hashemolhosseini, S., Brenner, H. R. (1999). Constitutively Active MuSK Is Clustered in the Absence of Agrin and Induces Ectopic Postsynaptic-Like Membranes in Skeletal Muscle Fibers. J. Neurosci. 19: 3376-3383 [Abstract] [Full Text]  
• Ferletta, M, Ekblom, P (1999). Identification of laminin-10/11 as a strong cell adhesive complex for a normal and a malignant human epithelial cell line. J. Cell Sci. 112: 1-10 [Abstract]  
• Brown, S., Fassati, A, Popplewell, L, Page, A., Henry, M., Campbell, K., Dickson, G (1999). Dystrophic phenotype induced in vitro by antibody blockade of muscle alpha-dystroglycan-laminin interaction. J. Cell Sci. 112: 209-216 [Abstract]  
• Miner, J. H., Cunningham, J., Sanes, J. R. (1998). Roles for Laminin in Embryogenesis: Exencephaly, Syndactyly, and Placentopathy in Mice Lacking the Laminin {alpha}5 Chain. JCB 143: 1713-1723 [Abstract] [Full Text]  
• Burstyn-Cohen, T., Frumkin, A., Xu, Y.-T., Scherer, S. S., Klar, A. (1998). Accumulation of F-Spondin in Injured Peripheral Nerve Promotes the Outgrowth of Sensory Axons. J. Neurosci. 18: 8875-8885 [Abstract] [Full Text]  
• McDearmon, E. L., Burwell, A. L., Combs, A. C., Renley, B. A., Sdano, M. T., Ervasti, J. M. (1998). Differential Heparin Sensitivity of alpha -Dystroglycan Binding to Laminins Expressed in Normal and dy/dy Mouse Skeletal Muscle. J. Biol. Chem. 273: 24139-24144 [Abstract] [Full Text]  
• Nielsen, P. K., Yamada, Y. (2001). Identification of Cell-binding Sites on the Laminin alpha 5 N-terminal Domain by Site-directed Mutagenesis. J. Biol. Chem. 276: 10906-10912 [Abstract] [Full Text]  
• Fujiwara, H., Kikkawa, Y., Sanzen, N., Sekiguchi, K. (2001). Purification and Characterization of Human Laminin-8. LAMININ-8 STIMULATES CELL ADHESION AND MIGRATION THROUGH alpha 3beta 1 AND alpha 6beta 1 INTEGRINS. J. Biol. Chem. 276: 17550-17558 [Abstract] [Full Text]  

This Article Abstract Full Text (PDF, 1390K) PPT slides of all figures Alert me when this article is cited Citation Map Services Email this article Similar articles in this journal Similar articles in PubMed Alert me to new content in the JCB Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Patton, B. L. Articles by Sanes, J. R. Search for Related Content PubMed PubMed Citation Articles by Patton, B. L. Articles by Sanes, J. R. Social Bookmarking                            What's this?